body{font-family:Arial,sans-serif;background:#f4f6f8;margin:0;color:#1f2937}.container{max-width:850px;margin:40px auto;padding:0 20px}.card{background:#fff;padding:20px;margin:20px 0;border-radius:10px;box-shadow:0 2px 10px #00000012}input{padding:10px;margin:5px;min-width:180px}button{padding:10px 14px;margin:5px;cursor:pointer}table{width:100%;border-collapse:collapse}th,td{text-align:left;padding:10px;border-bottom:1px solid #ddd}.error{padding:12px;background:#fff;border:1px solid #bbb}